Interspinous ligamentoplasty in the treatment of degenerative spondylolisthesis: midterm clinical results Clinical article

Object. Pseudarthrosis and adjacent-segment degeneration remain problems after fusion surgery. To overcome these complications, many dynamic stabilization methods have been developed. This study was conducted to elucidate the midterm results on the effectiveness of interspinous ligamentoplasty (ILP) to treat degenerative spondylolisthesis. Methods. Thirty-two consecutive surgeries involving decompression and ILP were performed by 2 surgeons at the authors' institution during 2001 and 2002. Nine patients were excluded from the study because of inadequate follow-up or radiological data, leaving a study population of 23 patients with a mean duration of follow-up of 64.6 months (range 60-77). All the patients had symptomatic spinal stenosis and Grade 1 spondylolisthesis at L4-5 level without foraminal stenosis and deformity. Clinical outcomes were evaluated by visual analog scale (VAS) for back and leg pain and the Oswestry Disability Index (ODI). Radiological measurements included segmental lordosis, total lumbar lordosis, posterior disc height, anterior slippage, angular motion, translational motion, and facet degeneration grade. Eighteen patients who had undergone bilateral laminotomy alone were included as a Control Group. Results. Twenty-two of the 23 patients who underwent ILP returned to their active daily lives. Symptomatic instability was less common in the ILP Group than in the Control Group (4.3% vs 27.8%). The mean postoperative VAS leg scores, VAS back scores, and ODI scores at final follow-up were significantly improved in both groups, in comparison to preoperative scores; however, the mean difference in ODI scores was significantly greater in the ILP group (29.3% vs 16.6%, p = 0.049). In radiological analysis, segmental and total lordoses were significantly increased in the ILP Group. In both groups slippage increased, disc height decreased, and angular motion was maintained, but translational motion decreased with statistical significance in the ILP Group, whereas it increased in the Control Group. Radiological instability was observed in 3 patients in the ILP Group, and 9 in the Control Group (significant between-groups difference, p = 0.016). Conclusions. Interspinous ligamentoplasty is a good option treating patients with Grade 1 degenerative spondylolisthesis requiring surgery. It is less invasive and effectively stabilizes the unstable spine with a relatively small incidence of postoperative instability. Interspinous ligamentoplasty provides satisfactory clinical and radiological results at midterm follow-up. (DOI: 10.3171/2010.3.SPINE0957)